
package com.lcj.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Static functions to simplifiy common {@link java.security.MessageDigest} tasks.  This
 * class is thread safe.
 
 *
 */
public class MD5Util {
	//被我改成公有的了
    private MD5Util() {
    }

    /**
     * Returns a MessageDigest for the given <code>algorithm</code>.
     * 
     * @param algorithm
     *            The MessageDigest algorithm name.
     * @return An MD5 digest instance.
     * @throws RuntimeException
     *             when a {@link java.security.NoSuchAlgorithmException} is
     *             caught
     */

    static MessageDigest getDigest() {
        try {
            return MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Calculates the MD5 digest and returns the value as a 16 element
     * <code>byte[]</code>.
     * 
     * @param data
     *            Data to digest
     * @return MD5 digest
     */
    public static byte[] md5(byte[] data) {
        return getDigest().digest(data);
    }

    /**
     * Calculates the MD5 digest and returns the value as a 16 element
     * <code>byte[]</code>.
     * 
     * @param data
     *            Data to digest
     * @return MD5 digest
     */
    public static byte[] md5(String data) {
        return md5(data.getBytes());
    }

    /**
     * Calculates the MD5 digest and returns the value as a 32 character hex
     * string.
     * 
     * @param data
     *            Data to digest
     * @return MD5 digest as a hex string
     */
    public static String md5Hex(byte[] data) {
        return HexUtil.toHexString(md5(data));
    }

    /**
     * Calculates the MD5 digest and returns the value as a 32 character hex
     * string.
     * 
     * @param data
     *            Data to digest
     * @return MD5 digest as a hex string
     */
    public static String md5Hex(String data) {
        return HexUtil.toHexString(md5(data));
    }  
    /**
     * Calculates the MD5 digest with the key and returns the value as a 32 character hex
     * string.
     * @param data : Data to digest
     * @param key - security key
     * @return
     */
    public static String md5Hex(String data, String key) {
    	String keyMd5 = HexUtil.toHexString(md5(key));
        return HexUtil.toHexString(md5(data+keyMd5));
    }  
   
    
  /* public static void main(String[] args)
   {
	   String data = "xjp0:14100001000";
	   System.out.println(md5Hex(data));
   }*/
}
